766a605380
2 Commits
| Author | SHA1 | Message | Date | |
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Kevin Lubick
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1f8c31b101 |
[infra] Add initial Bazel rules and files
These rules can be used to build our GMs on WASM+WebGL and libskia.a with just the CPU backend (and most other features turned off). This can be done with the following commands: - bazel build //modules/canvaskit:gm-bindings-wasm --gpu_backend=gl_backend --with_gl_standard=webgl_standard - bazel build :skia-core --config clang This pivots slightly from http://review.skia.org/463517 by using config_settings [1] instead of platforms for the optional features that we control. This pivot was suggested in [2] We have BUILD.bazel files in many of the subdirectories that specify filegroups for the appropriate files. In an effort to make //BUILD.bazel more readable, it is the responsibility of these subfolders to deal with conditionally including certain .h or .cpp files. This is done using select statements and config_settings or platform constraints as necessary. For example, src/gpu/BUILD.bazel will different private filegroups for each of the supported gpu backends [3] and a more-visible filegroup called "srcs" that has the right selection of the private files to be used for compilation. An effort has been made to avoid using glob() in our BUILD.bazel files. These file lists were made by using `ls -1` and some regex to add in quotes. We might want to make a helper script to assist with that, if necessary. To specify which options we have, the settings in //bazel/common_config_settings/BUILD.bazel have been redesigned. They make use of a macro `string_flag_with_values` that removes the boilerplate. Patchset 36 shows what the file looks like w/o the macro. The top level BUILD.bazel file will still need to use some logic to handle defines, because local_defines is a list of strings, not a list of labels [4]. Suggested Review Order: - WORKSPACE.bazel to see the new dependencies on the emsdk toolchain and bazel_skylib - bazel/common_config_settings/* to see the few settings defined (we have more to define, see BUILD.gn and //gn/skia.gni for ideas) - BUILD.bazel to see the "skia-core" cc_library rule. See also "gms" and "tests" - modules/canvaskit/BUILD.bazel to see the use of the emscripten "wasm_cc_binary" rule, which depends on the "skia-core", "gms", and "tests" rule. Note that it only builds some of the gms as a proof of concept. - The other BUILD.bazel files. Some of these are not platform or feature dependent (e.g. pathops). Others are (e.g. gpu). - All other files. [1] https://docs.bazel.build/versions/4.2.1/skylark/config.html#user-defined-build-settings [2] https://github.com/emscripten-core/emsdk/pull/920 [3] In this CL, that's just the webgl one. [4] https://docs.bazel.build/versions/main/be/c-cpp.html#cc_library.local_defines Change-Id: Ieecf9c106d5e3a6ae97d13d66be06b4b3c207089 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/458637 Reviewed-by: Ben Wagner <bungeman@google.com> Reviewed-by: Leandro Lovisolo <lovisolo@google.com> Owners-Override: Kevin Lubick <kjlubick@google.com> |
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Kevin Lubick
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4d41304def |
[infra] Add hermetic toolchain for C/C++ using Clang+Musl
This can successfully build a C library: bazel build --config=clang //third_party:libpng This can build and run a statically-linked executable: bazel test --config=clang //:bazel_test For more verbose compile and linking output, add the `--features diagnostic` flag to a Bazel command (see _make_diagnostic_flags() in toolchain/clang_toolchain_config.bzl. Similarly, a `--features print_search_dirs` can be used to show where clang is looking for libraries etc to link against. These features are made available for easier debugging. Suggested review order: - Read https://docs.bazel.build/versions/4.2.1/tutorial/cc-toolchain-config.html if unfamiliar with setting up C++ toolchains in Bazel - .bazelrc and WORKSPACE.bazel that configure use and download of the toolchain (Clang 13, musl 1.2.2) - toolchain/build_toolchain.bzl which downloads and assembles the toolchain (w/o installing anything on the host machine) - toolchain/BUILD.bazel and toolchain/*trampoline.sh to see the setup of the toolchain rules. - toolchain/clang_toolchain_config.bzl to see the configuration of the toolchain. Pay special attention to the various command line flags that are set. - See that tools/bazel_test.cc has made a new home in experimental/bazel_test/bazel_test.cpp, with a companion BUILD.bazel. Note the addition of some function calls that test use of the C++ standard library. The number being used to test the PNG library is the latest and greatest that verifies we are compiling the one brought in via DEPS (and not a local one). - third_party/* to see how png (and its dependent zlib) have been built. Pay special attention to the musl_compat hack to fix static linking (any idea what the real cause is?) - //BUILD.bazel to see definition of the bazel_test executable. Change-Id: I7b0922d0d45cb9be8df2fd5fa5a1f48492654d5f Bug: skia:12541 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/461178 Reviewed-by: Ben Wagner <bungeman@google.com> Reviewed-by: Leandro Lovisolo <lovisolo@google.com> |